WO2018214248A1

WO2018214248A1 - Wood microwave vacuum drying process for solid wood ground heating floor

Info

Publication number: WO2018214248A1
Application number: PCT/CN2017/092170
Authority: WO
Inventors: 王艳伟; 徐立; 黄毅玲; 孙龙祥
Original assignee: 久盛地板有限公司
Priority date: 2017-05-26
Filing date: 2017-07-07
Publication date: 2018-11-29
Also published as: DE112017007285B4; DE112017007285T5; CN108931108A

Abstract

A wood microwave vacuum drying process for a solid wood ground heating floor, comprising the following steps: a. placing a wood into a microwave treatment device, and starting the device; b. entering an accelerated drying stage: performing the first microwave radiation treatment on the wood when a moisture content of the wood is greater than 40-50%; c. entering a constant-rate drying stage: performing the second microwave radiation treatment on the wood when the moisture content of the wood ranges from 25% to 45%; d. entering a decelerated drying stage: performing the third microwave radiation treatment on the wood when the moisture content of the wood is smaller than 20-25%; and e. entering a cooling stage: cooling the wood, thereby completing microwave treatment of a floor. The drying process greatly improves the wood drying rate and the wood permeability, efficiently improves the wood drying quality, and improves the drying discharging rate.

Description

Microwave vacuum drying process for wood floor heating wood

Technical field

The invention relates to a microwave vacuum drying process for wood for solid wood floor heating, relating to the field of wood floor and furniture manufacturing.

Background technique

In recent years, with the improvement of people's consumption level, people pay more and more attention to high-quality home life experience. High-end home products are gradually popularized. “The solid wood floor enters the floor heating environment” has become an urgent demand of consumers. First, the solid wood floor heating floor has The natural advantages of comfortable feet, warm winter and cool summer, silent and non-slip, and adjustable temperature and humidity can significantly improve the comfort of the living environment. Secondly, consumers pay more attention to the environmental health of the home and begin to realize the natural environmental protection and green health. Solid wood flooring is the first choice for floor heating. In addition, the solid wood floor heating maintains the natural properties of the wood. The pattern is natural and beautiful, and the texture is unique. This is the quality that is not available in paving materials such as wood-based panels and ceramic tiles. From the "Ground Heating Hazard Theory" published in 2014, the "American Poisonous Floor Incident" in 2015, and the "Zhejiang Consumer Protection Committee and Shanghai Quality Supervision Bureau Product Spot Check" to the 2017 "CCTV Weekly Quality Report" Exposure events, regardless of their impact, but consumers' perception of the use of formaldehyde over-volatility in solid wood composite flooring in the floor heating environment has gradually deepened, whether the floor heating floor is healthy and becomes an untouchable bottom line, so the solid wood floor heating floor also shows Strong growth momentum. However, due to the long drying time, high energy consumption, poor drying quality and serious pollution of the wood, it is not very good. To meet market demand and environmental requirements, people began to seek and research new wood drying technology to achieve other auxiliary effects. Microwave vacuum drying technology originated in the 1930s and became a hot spot in the world due to the discovery of its thermal effects. Later in the 1960s and 1970s, many countries began to apply this technology to wood drying, but due to microwave drying technology. Immature, although it can significantly improve the drying rate of wood, but it is easy to damage the wood, can not effectively guarantee the quality of the wood after drying, it is difficult to achieve large-scale industrialization.

Summary of the invention

The technical problem to be solved by the present invention is to provide a microwave vacuum drying process for wood for solid wood floor heating. The invention not only greatly improves the drying rate of the wood, but also the invention can significantly improve the permeability of the wood, and provides favorable conditions for the subsequent production of the solid wood floor heating type such as flame retardant, silent, anticorrosive and dimensional stability improvement. At the same time, it effectively improves the drying quality of the wood and improves the drying yield.

In order to solve the above technical problem, the technical solution of the present invention is as follows: a microwave vacuum drying process for wood for warm floor heating, specifically comprising the following steps:

a. Put the wood into the microwave processing equipment and start the equipment for microwave treatment;

b. Accelerated drying stage: When the wood moisture content is above 40-50%, the first microwave irradiation treatment is carried out on the wood, the radiation power is 1.3-1.6KW, and the vacuum degree is adjusted to -0.065-(-0.07)Mpa, radiation Time 4-6min, the drying rate is maintained at 1.30 - 1.40% / min;

c. Constant-speed drying stage: when the wood moisture content is between 45% and 25%, the wood is The second microwave irradiation treatment, the radiation power is 0.8-1.2KW, the vacuum degree is maintained at -0.055-(-0.065)Mpa, the irradiation time is 18-25min, and the drying rate is maintained at 0.90-1%/min;

d. Deceleration and drying stage: When the wood moisture content is less than 20-25%, the wood is subjected to the third microwave irradiation treatment, the radiation power is 0.4-0.7KW, and the vacuum degree is maintained at -0.050-(-0.055)Mpa, the irradiation time For 13-17min, the drying rate is maintained at 0.5-0.6%/min;

e, cooling and cooling stage: cooling the wood to complete the microwave processing of the floor.

The above-mentioned wood microwave drying process for wood floor heating floor specifically includes the following steps:

b. Accelerated drying stage: When the wood moisture content is above 45%, the first microwave irradiation treatment is carried out on the wood, the radiation power is 1.45KW, the vacuum degree is adjusted to 0.068Mpa, the irradiation time is 5min, and the drying rate is maintained at 1.398%/ Min;

c. Constant-speed drying stage: When the wood moisture content is between 45% and 25%, the wood is subjected to a second microwave irradiation treatment, the radiation power is 1KW, the vacuum degree is maintained at -0.060Mpa, the irradiation time is 20min, and the drying is performed. The rate is maintained at 0.986%/min;

d. Deceleration and drying stage: When the wood moisture content is less than 25%, the wood is subjected to the third microwave irradiation treatment, the radiation power is 0.6KW, the vacuum degree is maintained at -0.052Mpa, the irradiation time is 15min, and the drying rate is maintained at 0.579%. /min;

In the aforementioned microwave microwave drying process for wood floor heating, the interval of the three microwave irradiation treatments is 2 min.

The above-mentioned wood floor heating floor wood microwave vacuum drying process, step d, cold But to 35 ° C.

The invention has the beneficial effects that compared with the prior art, the wood microwave drying treatment process of the invention can significantly improve the permeability of the wood, enhance the effect of the drying and humidity control treatment in the later stage, and also increase the drug loading amount. It has a positive effect on the anti-corrosion, flame-retardant and silent treatment of the heating floor in the subsequent order. At the same time, through the wood microwave modification treatment, the drying rate of the wood can be greatly accelerated, and the drying quality can be improved. Due to the use of microwave modification treatment, it will not Producing additional energy consumption and environmental pollution, in line with China's green environmental protection development philosophy, laying the foundation for the development of inferior materials in the entire timber industry. The wood treated by the present invention has the following characteristics through the applicant's test:

1. Increased dimensional stability: Southern pine is 8-10% higher than that of ordinary dry kiln in the dry place;

2, high efficiency and energy saving: in the microwave vacuum drying process, the southern pine is in the microwave field, the heating is carried out on the entire section, that is, the microwave heating has the permeability, so that the wood inside and outside is heated at the same time, the temperature rises at the same time. The moisture inside the wood quickly vaporizes, creating a pressure for outward diffusion. However, due to heat loss and evaporation of water on the surface of the wood, the internal temperature of the wood is actually higher than the surface temperature. When the internal temperature of the wood is higher than 100 ° C, the water vaporizes, generating steam pressure, accelerating the diffusion of moisture to the surface, and the drying speed is fast and the efficiency is high. Compared with conventional heating and drying, the heat of conventional heating and drying is conducted by conduction. The direction of heat transfer is opposite to the direction of water evaporation. Therefore, the heating rate is slow and the efficiency is low. The speed of microwave vacuum drying is independent of the thermal conductivity of wood. And depending on the intensity of the microwave field, that is, depending on the magnitude of the microwave power. The depth of microwave heating is related to the microwave frequency, and the electromagnetic frequency of the same frequency In terms of wave, the heating depth is related to the moisture content and material of the wood. The water content is large and the dielectric loss characteristics of the wood itself are large, and the heating depth is small. On the contrary, the heating depth is large. At present, the old floor of the wooden floor is the center of wood processing. Among them, wood drying is the main industry. The time required to treat southern pine with ordinary drying kiln is about 10-12 days. The drying time is too long, the drying cost is high, and the use is far. Infrared and steam energy for wood drying, the energy utilization rate is less than 50%, and the utilization rate of microwave as energy can reach more than 75%, and the energy consumption by far infrared and steam drying is reduced by more than 25%. The time required for the treatment of southern pine in this process is only about 1.2h, which greatly shortens the drying cycle and reduces the drying cost;

(3) Increase in wood utilization rate and yield rate: Southern pine wet material contains some mold and eggs, ordinary drying method can not completely kill eggs, etc., the microwave vacuum drying process can solve this problem and make wood utilization rate. Increase by 5% or more. During the drying process, the heating is uniform, so cracking and deformation are small. As long as the power level, vacuum degree and microwave irradiation time of the microwave treatment are controlled, the quality is easily ensured, the wet heart phenomenon does not occur, the drying is uniform, and the residual stress is small. Microwave vacuum dried wood surfaces retain their original natural color. The yield of microwave vacuum drying of Southern Pine was also significantly improved. The output rate of microwave vacuum drying reached 98%, which was 5% higher than conventional drying, and the effect was obvious.

detailed description

Embodiment 1: a microwave vacuum drying process for wood floor heating wood, specifically comprising the following steps:

1. Material selection: Southern Pine, size 1000mm × 135mm × 26mm, initial moisture content 50-55%.

2, accelerated drying stage: moisture content (water content inspection board) more than 45%, microwave power 1.6KW, vacuum -0.069MPa, radiation time 4min, drying rate is about 1.365% / min;

3, constant speed drying stage: when the water content is between 45-25%, the power size is 0.8KW, the vacuum degree is -0.063MPa, the irradiation time is 24min, and the drying rate is 0.92%/min;

4. Deceleration and drying stage: when the water content is <25%, the power is 0.51KW, the vacuum is -0.050MPa, the irradiation time is 17min, and the drying rate is 0.52%/min;

5. Cooling and cooling stage: Turn on the cooling system to cool down, wait until the temperature drops to 25 °C, and complete the microwave treatment process of the floor.

Embodiment 2: Wood microwave drying process for wood floor heating, specifically comprising the following steps:

2, accelerated drying stage: moisture content (water content inspection board) more than 45%, microwave power 1.45KW, vacuum -0.068MPa, radiation time 5min, drying rate is about 1.398% / min;

3, constant speed drying stage: when the water content is between 45-25%, the power size is 1.0KW, the vacuum degree is -0.060MPa, the irradiation time is 20min, and the drying rate is 0.986%/min;

4. Deceleration and drying stage: when the water content is <25%, the power is 0.6KW, the vacuum is -0.052MPa, the irradiation time is 15min, and the drying rate is 0.579%/min;

5. Cooling and cooling stage: Turn on the cooling system to cool down, wait until the temperature drops to 35 °C, and complete the microwave treatment process of the floor.

Claims

The wood microwave vacuum drying process for solid wood floor heating is characterized in that the following steps are specifically included:

a. Put the wood into the microwave processing equipment and start the equipment for microwave treatment;

b. Accelerated drying stage: When the wood moisture content is above 40-50%, the first microwave irradiation treatment is carried out on the wood, the radiation power is 1.3-1.6KW, the vacuum degree is adjusted to -0.065～-0.07Mpa, and the irradiation time is 4 -6min, the drying rate is maintained at 1.30 - 1.40% / min;

c. Constant-speed drying stage: When the wood moisture content is between 45% and 25%, the second microwave irradiation treatment is performed on the wood, the radiation power is 0.8-1.2KW, and the vacuum degree is maintained at -0.055--0.065Mpa. The irradiation time is 18-25min, and the drying rate is maintained at 0.90-1%/min;

d. Deceleration and drying stage: When the wood moisture content is less than 20-25%, the wood is subjected to the third microwave irradiation treatment, the radiation power is 0.4-0.7KW, the vacuum degree is maintained at -0.050～-0.055Mpa, and the irradiation time is 13 -17min, the drying rate is maintained at 0.5-0.6% / min;

e, cooling and cooling stage: cooling the wood to complete the microwave processing of the floor.
The wood microwave vacuum drying process for solid wood floor heating according to claim 1, characterized in that the method comprises the following steps:

a. Put the wood into the microwave processing equipment and start the equipment for microwave treatment;

b. Accelerated drying stage: when the wood moisture content is above 45%, the wood is first One microwave radiation treatment, the radiation power is 1.45KW, the vacuum degree is adjusted to 0.068Mpa, the irradiation time is 5min, and the drying rate is maintained at 1.398%/min;

c. Constant-speed drying stage: When the wood moisture content is between 45% and 25%, the wood is subjected to a second microwave irradiation treatment, the radiation power is 1KW, the vacuum degree is maintained at -0.060Mpa, the irradiation time is 20min, and the drying is performed. The rate is maintained at 0.986%/min;

d. Deceleration and drying stage: When the wood moisture content is less than 25%, the wood is subjected to the third microwave irradiation treatment, the radiation power is 0.6KW, the vacuum degree is maintained at -0.052Mpa, the irradiation time is 15min, and the drying rate is maintained at 0.579%. /min;

e, cooling and cooling stage: cooling the wood to complete the microwave processing of the floor.
The microwave vacuum drying process for wood for solid wood floor heating according to claim 1 or 2, wherein the interval of the three microwave radiation treatments is 2 min.
The microwave vacuum drying process for wood for wood floor heating according to claim 1 or 2, wherein in step e, cooling to 35 °C.